Apparatus for enhanced human-powered locomotion

ABSTRACT

A foot or shoe-borne apparatus comprises a spacer and spring assembly that can be oriented in two orientations. In the first orientation, the assembly is under the sole of a user&#39;s foot or shoe such that the assembly acts against the ground for enhanced locomotion for that foot or shoe. In the second orientation, the assembly is positioned away from the sole of the foot or shoe, thereby enabling ordinary use of that foot or shoe.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of and priority to Canadian PatentApplication No. 2,812,815 filed Apr. 9, 2013 the entirety of which isincorporated herein by reference.

TECHNICAL FIELD

The invention relates to apparatus for human-powered locomotion. Inparticular the apparatus is a foot-borne device which can be used forenhanced skateboarding, walking, running, jumping and other human footmovement.

BACKGROUND OF THE INVENTION

There are few effective foot-borne devices for use by users which canassist in movement.

There is a need to provide

BRIEF SUMMARY OF THE INVENTION

The invention provides a foot-borne or shoe-borne spacer and springassembly that can be quickly and easily configured in one of twoorientations: a first, so-called ‘down’ orientation in which the spacerand spring assembly engages the ground and enables spacer andspring-assisted locomotion, and a second, so-called ‘up’ orientation inwhich the spacer and spring assembly does not engage with the ground andwhich allows normal use of the foot and shoe as in ordinary, un-assistedlocomotion, standing, or resting etc.

In what follows, the ground-engaging orientation of the spacer/springassembly will be referred as the ‘down’ orientation. The groundnon-engaging orientation will be referred as the ‘up’ orientation.

The invention enables spacer/spring-assisted, foot-based locomotion whenthe spacer/spring assembly is ‘down’ and also enables ordinarynon-spacer/spring-assisted use of the foot and shoe when thespacer/spring assembly is ‘up.’ The invention furthermore allows for theeasy and rapid reconfiguration of the spacer/spring assembly from ‘down’to ‘up’ (and vice-versa) at the user's discretion. In other words, theuser can easily and rapidly affect a change from one orientation to theother.

Taking an example wherein the user is skateboarding, a device of theinvention with spacer/spring assembly ‘down’ enables aspacer/spring-assisted power-stroke that propels the user and skateboardforward. When the user places the spacer/spring in the ‘up’ position,the invention allows normal functioning of the user's foot and shoe,including, in the present example, normal skateboarding, standing on theskateboard during gliding, as well as walking or any other activity offthe skateboard.

Depending on the specifics of the user's body ergonomics, the inventionin the ‘down’ position may assist the user in any or all of thefollowing ways: increasing efficiency of the user's motion, extendingthe reach of the user's power-stroke, minimizing vertical displacementsof the user's center-of-mass, performing energy recovery to the user'sfoot during the end of the power-stroke, improving ergonomics orcomfort, and absorbing shock that would otherwise occur between theuser's foot and the ground.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a first embodiment of the invention, showingthe spacer/spring assembly in the ‘down’ orientation.

FIG. 2 is a side view of a first embodiment of the invention, showingthe spacer/spring assembly in the ‘up’ orientation.

FIG. 3 is a side view of a second embodiment of the invention, showing ahinged, sheathed pogo type spacer/spring assembly, in the ‘down’orientation (solid lines) and the ‘up’ orientation (dashed lines);

FIGS. 4 a and 4 b illustrate detailed views of the spacer/springassembly of the second embodiment of the invention, showing thespacer/spring assembly in the ‘down’ orientation and locked (4 a) aswell as the same spacer/spring assembly in the ‘up’ orientation (4 b);

FIGS. 5 a and 5 b illustrate a third embodiment of the invention inwhich the ‘up’ and ‘down’ orientations are effected by a lever formanual rotation by the user.

FIGS. 6 a, 6 b, 6 c and 6 d illustrate a sample wireframe secondaryspacer/spring that is appropriate for use in the first embodiment ofFIGS. 1 and 2.

FIGS. 7 a and 7 b illustrate a fourth embodiment of the invention.

FIGS. 8 a and 8 b illustrate a fourth embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The apparatus of the present invention provides for a foot or shoe-bornespacer/spring that can be quickly and easily oriented in either of twodistinct orientations, a ‘down’ orientation which allows thespacer/spring to engage with the ground, thus enablingspacer/spring-assisted locomotion, and an ‘up’ orientation in which thespacer/spring does not engage with the ground and thus allows normal useof the foot and shoe. These two orientations are referred to as the‘down’ and ‘up’ orientations, respectively.

To describe the two orientations more precisely, consider that the‘down’ orientation refers to the condition in which the spacer/springassembly is positioned below the sole of the user's foot/shoe and isdirected more or less perpendicularly to the sole of the user'sfoot/shoe. In this orientation the spacer/spring is able to engage withthe ground when the user performs a power stroke, that is, when the soleof the user's foot/shoe exerts a force against the ground. In thisorientation the spacer/spring assembly can act as a spacer thatpositions the user's foot in a posture advantageous for ergonomics. Thiscan also create compression in the spacer/spring, thereby storingenergy, which can be subsequently released at the end of the powerstroke, that is, upon removal of the compressive force, therebyenhancing the efficiency and possibly the force of the power-stroke.

In the ‘up’ orientation, the spacer/spring assembly is positioned awayfrom the bottom of the sole of the user's foot/shoe. The spacer/springassembly is instead oriented above the foot/shoe or beside thefoot/shoe. In the ‘up’ orientation the spacer/spring subsystem no longerengages with the ground during normal use of the foot/shoe and thuspermits normal use of the foot/shoe, that is, non-spacer/spring-assisteduse of the foot/shoe as in ordinary locomotion, resting, or standing,etc.

One advantage of the invention is that the apparatus can be construed tofit the user's existing shoe. A second advantage is that the user isable to easily and quickly change the orientation of the spacer/spring,in some cases, in the midst of physical activity. This is describedbelow after first summarizing the distinct functional subsystems.

The invention in all its manifestations and embodiments includes threefunctionalities. Each functionality is usually, but not necessarily,embodied in its own mechanical subsystem: (S1) a spacer orspacer/spring; (PAL2) a pivot, actuator and lock, and (A3) an attachmentto the user's foot/shoe and even the user's body.

(S1) Spacer/Spring Functionality

The spacer/spring functionality (S1) while in the ‘down’ position,enhances the power stroke of the user's locomotion. This is by way ofthe mediating influence of the spacer/spring when it is positionedbetween the shoe and the ground.

(PAL2) Pivot, Actuator, and Lock Functionality

The pivot of the PAL2 functionality represents a hinge or swivelingmeans that allows the spacer/spring to be oriented in either of the twopossible orientations, ‘down’ or ‘up.’ The particular orientation at anygiven moment is chosen at the user's discretion, by way of an actuationmeans that also comprises the PAL2 functionality. Finally, the lockfunction of the PAL2 functionality refers to the means by which thespacer/spring, while in the ‘down’ position, is held firmly in positionduring the power-stroke.

The PAL2 subsystem, along with the other subsystems, must also performan additional function, namely the function that ensures that the twoconfigurations of the spacer/spring (‘down’ and ‘up’) representmechanically quasi-stable configurations. In other words, thespacer/spring should rest in each orientation and should notspontaneously change orientation under the influence of weak, randomforces such as those caused by inertia, wind, or inadvertent contactwith the user's clothing or road debris etc. On the contrary, thespacer/spring's orientation should be changed only by way of anintentional, but simple, user-actuation as described herein.

The system should have minima in the mechanical self-energy function atboth the ‘down’ and ‘up’ orientations. This can be realized by way ofdetents or ‘catches’ built into the S1 and PAL2 subsystems. Thesequasi-stable resting are distinct from the locked ‘down’ positionmentioned previously. The latter ensures the spacer/spring remainsfirmly in the ‘down’ position during the power stroke. This is furtherelaborated in the descriptions below.

(A3) Attachment Functionality

The attachment functionality (A3) embodies the means by which theinvention can be fastened to the user's body. Depending upon theparticular embodiment, this can include the user's foot, ankle, shoe,leg, and hip.

The three subsystems are best understood by considering the drawings inlight of the examples.

Example 1

FIGS. 1 and 2 show a first embodiment of the invention. FIG. 1illustrates the ‘down’ position, in which the spacer/spring assembly S1is positioned below the foot. FIG. 2 illustrates the ‘up’ position,showing the spacer/spring behind and above the heel area of the foot.

This embodiment of the invention illustrates an apparatus 5 comprisingtwo parts: a first ‘primary’ spacer/spring 10, and a second, ‘secondary’spacer/spring 11. The primary spacer/spring 10 is designed tosimultaneously contact the ground and the sole of the user's shoe whenin the ‘down’ position. The secondary spacer/spring 11 is designed toenable pivoting of spacer/spring 10 between ‘down’ and ‘up’ positions.The secondary spacer/spring 11 also possesses inherent spring-likeproperties in order to accommodate compression travel of the primaryspacer/spring when under compression, such as from the weight of thefoot. The secondary spacer/spring must also realize PAL2 functionalityvia its coupling to the hinge 20 as will be described below.

In this first embodiment, the primary spacer/spring 10 takes the form ofa sphere or cylinder constructed of a robust material, preferably withinherent elastic properties. Appropriate materials include but are notrestricted to metal or composite flat-form springs, coil compressionsprings, solid urethane foam or rubber, or hollow polymer balls orcylinders. Other materials having elastic properties are contemplated.

The secondary spacer/spring 11 is a stirrup-shaped or generally‘U’-shaped wire-form constructed of materials commonly used for springs,such as ‘spring steel’ and the like.

The secondary spacer/spring 11 attaches to strap 30 via a hinge 20.Strap 30 can be worn by user on the foot or be attached to user's shoe.Alternatively, strap 30 may be an integral part of a shoe. Detents orgrooves on the outer edges of hinge 20 can partially realize the PAL2functionality of quasi-stable resting states for the ‘down’ and ‘up’orientations. More precisely, the secondary spacer/spring 11 and thehinge 20 can be designed so that their mechanical coupling producesquasi-stable ‘down’ and ‘up’ configurations. The locking feature of PAL2is realized by the shape of the secondary spring 11 which includesre-curve 12 and by the fact that the primary spacer/spring 10 contactsthe sole of the user's foot/shoe, thus providing a locking force duringthe power stroke.

The attachment functionality A3 is realized by a strap subsystem thatcan straps onto user's foot or user's shoe by way of strap 30 and heelcup 31. Both strap 30 and heel cup 31 can have adjustment means toensure snug fit and user comfort.

In this embodiment, strap 30 and heel cup 31 transcribe the outerperimeter of the foot/shoe. These may optionally incorporatereinforcement such as metallic bands for extra strength. Alternatively,the attachment functionality A3 can be built into a specially designedand customized shoe. This can be readily realized by gluing orpermanently embedding or fastening pivot 20 into the shoe itself.

As illustrated in FIGS. 1 and 2, apparatus 5 allows the primaryspacer/spring 10 to rotate around user's heel, thus enabling the twoconfigurations. In the ‘down’ configuration the primary spacer/spring 10mediates the user's power stroke against the ground. In the ‘up’position the primary spacer/spring 10 is lifted away from the sole ofthe foot/shoe, thus allowing for more-or-less normal operation of thefoot/shoe.

As indicated previously, the meta-stability and the locking aspects ofthe PAL2 functionality are realized by judicious design of the couplingbetween the primary spacer/spring 10 and the hinge 20. An alternativedesign comprises the secondary spacer/spring 11, constructed of amaterial such as spacer/spring steel and possessing some residualtension, that presses its lateral sections against the mating lateralsurface of the coupling. Concurrently, hinge 20 is constructed withappropriate grooves that act as detents.

By proper design of all the mating surfaces between the secondaryspacer/spring 11 and the hinge 20, apparatus 5 provides a meta-stableresting points for the spacer/spring while in the ‘down’ and ‘up’positions.

The actuation means of this embodiment of the invention is realized byway of the shape of the S1 subsystem. Staring from the ‘down’orientation, the user can achieve the ‘up’ configuration seen in FIG. 2by lifting the foot/shoe off the ground and by applying a scrapingmotion of the user's foot/shoe relative to the ground in such a manneras to avoid to compression of primary spacer/spring 10 but insteadachieving the swiveling of the spacers/springs 10, 11 into the ‘up’configuration of FIG. 2.

Starting from the ‘up’ position the user can achieve the ‘down’ positionby manually pushing the spacer/springs 10, 11 down or by performing ascraping motion of the heel against the shin of the opposite leg oragainst any other convenient surface.

The apparatus 5 allows the user to easily and conveniently set thespacer/springs 10, 11 into either ‘up’ or ‘down’ meta-stable positions.The user thus has freedom to freely transition the spacer/springs 10, 11between its two orientations and thus deploy the spacer/springs 10, 11during the power-stroke of spacer/spring-assisted locomotion, and toremove the spacer/springs 10, 11 from the bottom of the foot/shoe whenordinary use of the foot/shoe is desired.

As indicated previously, in this embodiment the locking functionality ofthe PAL2 sub-system is achieved by the re-curve 12 of the secondaryspacer/spring 11. This can also be achieved by appropriate modificationsto the coupling hinge 20. These features ensure that when the apparatus5 is in the ‘down’ position, the system locks into position as long as asuitable compression force is maintained between the foot/shoe and theground. When the compression force is removed, the system returns to themetastable ‘down’ position which is easily altered by the user asdescribed above.

To illustrate an embodiment of the wire-frame secondary spring 11,supplementary FIGS. 6 a, 6 b, 6 c and 6 d are provided. FIG. 6 aillustrates one embodiment of the wireframe as it appears when heldapproximately vertical, looking down. FIG. 6 b illustrates oneembodiment of the wireframe as it appears sitting on a bench with thecurve oriented upwards. FIG. 6 c) illustrates one embodiment of thewireframe as it appears in a perspective side view. FIG. 6 d)illustrates a side view of one embodiment of the wireframe, showing anapproximate 80 degree angle between the attachment portion and mainportion. Other angles between portions of the wireframe arecontemplated.

It is noted that that the specific features of the invention are in noway limiting of the invention and are merely examples of practicalrealizations of the invention. For example, it is not necessary for thepivot to be located behind the heel. Instead, other embodiments can beconstrued with the pivot located closer to the front of the foot.Similarly, other variants can be contrived that enable an ‘up’ positionat the side of the shoe. The generality of the invention can be furtherillustrated by considering other embodiments of the invention as in thefollowing examples.

Example 2

FIG. 3 illustrates a second embodiment of the present invention. In thisembodiment, the apparatus 5′ comprises a compressive spacer/spring 10′(shown in cutaway) that is housed inside a tube or sheath 11′. Thespacer/spring 10′ is connected to a shaft or piston 12′ that isoptionally terminated at its lowest end with a pad 13′ for contactingthe ground.

The ‘down’ configuration is delineated by solid lines in FIG. 3. This isthe default or resting configuration of the spacer/spring system in thisembodiment of the invention. The ‘up’ configuration, delineated withdotted lines in FIG. 3 and is achieved by pivoting the spacer/springassembly upward and backward, toward the heel of the shoe. This isenabled by the hinge 20′, which is built into the piston or shaft 12′and which embodies the pivoting and locking means of the PAL2functionality of the invention in this embodiment.

As in the previous embodiment of the invention, the attachmentfunctionality A3 is accomplished by way of straps 30′, 31′, and 32′,which hold the sheath 11′ in place against the side of the shoe and theuser's ankle.

In this embodiment, the locking means required by PAL2 functionality isautomatically achieved when the spacer/spring assembly is compressed bythe action of the user's foot. This is realized by ensuring that thehinge 20′ is situated near the lower portion of the shaft 12′ in such away that even slight compression pushes the hinge 20′ into the sheath11′ and prevents any rotation of the hinge, thereby preventing thespacer/spring subsystem from moving into the ‘up’ configuration. This isillustrated in FIGS. 4 a and 4 b, which show the ‘up’ and ‘down’positions respectively, of the spacer/spring sub-system including thehinge 20′.

The meta-stability of the ‘up’ configuration is realized by the artificeof a friction-stop 34′ consisting of a knob, flexible hook, ridge, ormating depression on the strap that accepts the lower portion of thespacer/spring assembly shaft 12′ and/or the pad 13′ and thus maintainsthe lower portion of the spacer/spring assembly in the ‘up’ orientationduring ordinary functioning of the shoe.

Actuation of the system is accomplished either manually or by scrapingthe side of the shoe against the ground. For example, the pad 13′provides a convenient surface for the user to manually release the shaft12′ from the ‘up’ position and to thus initiate the ‘down’ position asneeded for a spacer/spring-assisted power stroke of the foot against theground. Alternatively, the ‘up’ configuration can be achieved by theuser removing pressure from the spacer/spring assembly by lifting thefoot off the ground and by manually rotating the piston backward or byapplying a diagonal downward and forward force, as in a scraping motion,that does not compress the spacer/spring but instead forces the shaft12′ into the ‘up configuration.

To summarize, characteristic features of this second embodiment of theinvention are: (a) the spacer/spring assembly 10, 11, positionedlaterally on the shoe; (b) the spacer/spring assembly utilizes apiston-type action, and (c) the ‘up’ configuration is achieved bypivoting the spacer/spring assembly backward, toward the back of theshoe.

As discussed with the previous, first embodiment, the specific featuresof the second embodiment are in no way limiting of the invention and areexamples of practical realizations of the more general, essentialfunctionalities of the invention. For example, the ‘up’ and ‘down’orientations of the second embodiment are achieved by hinge 20′. This isillustrative of the general principle and an alternate design could bearranged which does not use a hinge but instead wherein thespacer/spring is connected to a solid, non-hinged piston and the pistonand sheath are so arranged at their upper ends so that when thespacer/spring is fully compressed, the piston protrudes through the topof the sheath where a latch would be implemented to maintain thespacer/spring compression and thus the ‘up’ configuration indefinitely.

The generality of the invention can be further illustrated byconsidering a third embodiment of the invention in the following.

Example 3

FIGS. 5 a and 5 b illustrate respectively, the ‘down’ and ‘up’ positionsof a third embodiment of the present invention. This embodiment has somesimilarity with the second embodiment illustrated in FIGS. 3, 4 a, and 4b because both embodiments incorporate a sheathed spacer/springassembly.

In keeping with the numbering used in the previous, second embodiment,the apparatus of the third embodiment is numbered 5″ in FIGS. 5 a and 5b. The spacer/spring 10″ is housed inside the sheath 11″.

This third embodiment of the invention differs from the secondembodiment because the PAL2 functionality is realized by way of a handle20″ which is contiguous to the piston or shaft 21″ and whose lowerterminus has a contact 22″ that engages with the ground. By way of thehandle 20″ the user can manually couple or decouple the shaft 21″ fromthe internal spacer/spring 11″. This is accomplished by providing theshaft 21″ with an internal shelf or notch, not illustrated in FIGS. 5 aand 5 b, which couple or decouple the shaft 21″ to the spacer/spring,depending on the angle of rotation.

As in the previous figures the attachment functionality A3 is realizedby way of straps 30″ and 31″.

To summarize, the characteristic features of this third embodiment ofthe invention are: (a) the spacer/spring assembly 10″ is situatedlaterally on the shoe and the ground contacting portion of thespacer/spring assembly is positioned beneath the ball or heel of theuser's foot; (b) the PAL2 functionality is realized by means of arotating action, affected via the user's hand, and, (c) the ‘upconfiguration rotates the spacer/spring assembly backward and upward,toward the heel of the shoe.

Example 4

FIGS. 7 a and 7 b together illustrate a fourth embodiment of theinvention. FIG. 7 a shows the spacer/spring assembly in the ‘down’orientation. FIG. 7 b shows the spacer/spring assembly in the ‘up’orientation. One of the noteworthy characteristics of this embodiment isthat the wire form is configured in such a way as to rest against thesole of the shoe when in the ‘down’ position (FIG. 7 a).

FIGS. 8 a and 8 b together illustrate a fifth embodiment of theinvention. As with the previous case, FIGS. 8 a and 8 b respectivelyshow the spacer/spring assembly in the ‘down’ and ‘up’ orientations. Oneof the characteristics of this embodiment is that the wire form does notrest against the sole of the shoe while in the ‘down’ position (FIG. 8a).

Both embodiments illustrated in FIGS. 7 and 8 possess two distinguishingfeatures: the first feature is the use of apparatus components that arebuilt-in to the shoe. The second feature is the use of secondary springsto ensure that both the ‘down’ and ‘up’ positions of the mainspacer/spring assembly are stable.

The embodiments of these figures also illustrate several secondary,optional features for illustrative purposes. These concern thecomposition of the main spacer/spring and the location of the axlehousings. Specifically, the embodiment of FIG. 1 possesses a mainspacer/spring comprised of a tongue of spring steel or fiber-reinforcedcomposite. This embodiment also uses an axle housing that is built-in(i.e. embedded) into the sole of the shoe.

By contrast, the embodiment of FIG. 2 possesses a main spacer/springcomprised of a ball of elastomeric material such as closed-cellpolyurethane. This embodiment uses an axle housing that is affixed tothe back heel of the shoe. In both cases, these secondary features areillustrative are not essential or necessary features of the respectiveembodiments; they are, in fact, interchangeable, and are shown forillustrative purposes only, to present several advantageous means toembody the broader aspects of the invention.

FIGS. 7 a and 7 b show an embodiment of the invention that is built-into the shoe (20) and that utilizes secondary springs 14 to helpestablish the stable ‘down’ and ‘up’ positions of the main spacer/springassembly.

FIG. 7 a illustrates the ‘down’ position, in which the mainspacer/spring 10 is positioned below the foot. FIG. 7 b illustrates the‘up’ position, in which the main spacer/spring 10 is positioned behindand above the heel of the foot.

The main spacer/spring 10 is connected to pivot system 11, which in thisembodiment is comprised of a wireframe. The main spring 10 may beconnected to the frame 11 in either permanent or impermanent manner, thelatter facilitating replacement of the main spring for maintenance andrepair.

Although it is shown in side profile in the figures, the wire frame 11is essentially a bent rectangle of resilient material such as springsteel wire. Wire frame 11 has two free ends of wire whose proximal wiresegments are bent at approximately 90 degrees to the rectangle, suchthat the free ends can be inserted into opposite ends of the axlehousing 20 and thus establishing mating of the two sub-systems 11 and20.

A notable feature of this embodiment resides in the shape of the wireframe 11. In the ‘down’ position, the rectangular portion of thewireframe rests against the sole of the shoe. The wire frame 11 thuspositions the main spring 10 (to which it is attached) under the shoe asillustrated in FIG. 7 a, thereby providing stability of the mainspacer/spring under the foot.

The wire frame 11 also possesses attachment means 13—one on either sideof the shoe (but with only one secondary spring 14 visible in thefigures). Secondary 14 are stretched between fastening point(s) 12 onthe wireframe and fastening point(s) 13 on the shoe. The latter point(s)13 can be screwed into the material of the shoe or built-in to the shoeduring manufacture.

In combination with the wire frame 10 and axle housing 20, the secondarysprings 14 ensure that the ‘down’ and ‘up’ orientations of the springassembly are stable while the in-between orientations are not stable.They also ensure smooth operating action of the spring assembly so thatthe user can transition smoothly between the ‘down’ and ‘up’ states.

The axle housing 20 is comprised of a metal or plastic tube that can beinserted into an existing shoe or that can be built-in to a specialized,purpose-built shoe during manufacture. For illustrative purposes, theaxle housing 20 is embedded inside the material of the shoe. This is nota defining feature of the embodiment. Alternate locations for the axlehousing, such as behind the heel, are also possible.

For similarly illustrative purposes, the main spacer/spring 10 shown inFIG. 7 takes the form of a tongue of spring-steel or fiber-reinforcedcomposite. Again, this is for illustrative purposes and other types ofmain springs may also be used.

To summarize, the essential features of the embodiment of FIG. 7 are:(a) a wire frame that rests against the sole of the shoe, (b) a built-inaxle housing that is embedded within the material of the shoe (notnecessarily the sole); (c) secondary springs that establish thestability of the ‘down’ and ‘up’ orientations of the spring assembly.

FIGS. 8 a and 8 b show a second embodiment of the invention that isbuilt into the shoe and that utilizes secondary springs to help toestablish the stable ‘down’ and ‘up’ positions of the main spacer/springassembly.

FIG. 8 a illustrates the ‘down’ position, in which the mainspacer/spring 10 is positioned below the foot. FIG. 8 b illustrates the‘up’ position, in which the main spacer/spring 10 is positioned behindand above the heel of the foot.

A key feature of this embodiment resides in the shape of the wire frame11. This wire frame (shown in side profile in the figures) isessentially a bent rectangle with two free ends. In contrast to the wireframe of FIG. 7, the present wire frame is bent at greater than 90degrees. As before the free ends of the wireframe are inserted intoopposite ends of the axle housing 20. In this case however no part ofthe wireframe rests against the sole of the shoe when ‘down.’ Instead,and in contrast to the embodiment of FIG. 7, a gap remains between thewire frame and the sole of the shoe. This allows a portion of the mainspacer/spring 10 to be positioned in contact with the sole of the shoeas illustrated in FIG. 8 a.

The wire frame 11 also possesses attachment means for secondary springs14—one on either side of the shoe (but with only one spring 14 visiblein the figures). The springs 14 are stretched between fastening point(s)12 on the wireframe and a fastening point(s) 13 on the shoe. The latterpoint(s) 13 can be screwed into the material of the shoe or built-in tothe shoe during manufacture.

In combination with the wire frame 10 and axle housing 20, the secondarysprings 14 ensure that the ‘down’ and ‘up’ positions of the springassembly are stable and that the in between orientations are not stable.They also ensure smooth operating action of the spring assembly so thatthe user can transition smoothly between the ‘down’ and ‘up’ states.

The axle housing 20 is comprised of a metal or plastic tube that can bebuilt-in to a specialized, purpose-built shoe during manufacture. Forillustrative purposes, the axle housing 20 is affixed to the back of theheel of the shoe. The heel location of the axle housing 20 is not adefining feature of the embodiment, however. Alternate locations for theaxle housing, such as inside the sole or heel are also possible.

For similarly illustrative purposes the main spacer/spring 10 shown inFIG. 8 takes the form of a spheroid of closed-cell polyurethane foam.This too is for illustrative purposes and other types of main springsare possible.

To summarize, the essential features of this embodiment are: (a) a wireframe that does not rest against the heel of the shoe but that allows aportion of the main spring to directly contact the sole of the shoe, (b)a built-in axle housing that is affixed to the material of the shoe (notnecessarily the heel); (c) secondary springs that establish thestability of the ‘down’ and ‘up’ orientations of the spring assembly.

The above figures represent embodiments of the invention and in no waylimit the general principle of the invention. For example, variants ofthe invention can be envisioned which are placed toward the front of thefoot.

The invention can be embodied as a so-called ‘retrofit’ system thatstraps onto pre-existing footwear such as running shoes or to the user'sbare foot or socked foot. Alternatively, the invention can be integratedwithin a customized shoe with pivot and actuating assembly beingincorporated directly into the design of the shoe.

The invention enables enhanced locomotion with improved efficiency,ergonomics, and entertainment value of human foot-based locomotion. Theinvention is particularly well suited for skateboarding. Due to the twoorientations of the spacer/spring assembly, a skateboarding user canquickly place the spacer/spring in the ‘down’ position when that footperforms a power-stroke against the ground and to place thespacer/spring assembly in the ‘up’ configuration when the same footrests on the skateboard or when the user is off the skateboard.

1. A spring assembly attachable to a strap on a user's foot or shoe,comprising a pivot coupled to the strap configured to allow the springassembly to pivot into a first quasi-stable orientation, whereby thespring assembly contacts the ground for spring-assisted use of the footor shoe, and a second quasi-stable orientation, whereby the springassembly does not contact the ground for normal, non-spring-assisted useof the foot or shoe.
 2. The spring assembly of claim 1 wherein the pivotpossesses a lever or handle that facilitates pivoting the springassembly from the first to the second orientation and back.
 3. Thespring assembly of claim 1 wherein the pivot comprises a mechanism thatprovides for the first quasi-stable orientation to be further stabilizedor momentarily mechanically locked under forces generated by the actionof the foot or shoe contacting the ground.
 4. The spring assembly ofclaim 1, further comprising additional housings, straps, and fasteningmeans, configured to allow the spring assembly to be housed, strappedand fastened to a shoe.
 5. The spring assembly of claim 1 wherein thespring assembly is integral to a shoe.
 6. The spring assembly of claim1, wherein the spring assembly is chosen from the group consisting ofcoil springs, wave springs leaf springs, solid composite springs, andwireframes; air bladders, rubberized materials, and solid or quasi-solidcompressive materials.
 7. The spring assembly of claim 1, wherein thespring assembly includes stiff members to effect ground-contact andshoe-contact of the spring assembly, the stiff members coupled by acompressive member comprising one or more of coil springs, wave springs,leaf springs, solid composite springs, wireframes; air bladders, otherrubberized materials, and solid or quasi-solid compressive materials.